This invention relates to diamond doping.
The doping of diamond with atoms such as boron, nitrogen, phosphorus, arsenic and the like is known. One such method, described in European Patent No. 0209257, is to create a damaged layer within the diamond by bombardment at low temperature, i.e. that of liquid nitrogen, introduce dopant atoms into the damaged layer at the same, or a similar, low temperature, and then anneal the damaged layer to cause dopant interstitial atom to diffuse to lattice positions and to reduce the lattice damage. The annealing may be rapid annealing.
European Patent Publication No. 0 573 312 describes a similar method to that described above, save that the steps of creating the damaged layer, introducing the dopant atoms and rapid annealing of the doped product is repeated several times until a doped diamond having a desired amount of dopant is produced.
In these methods, the dose of the ion implantation will vary according to the nature and energy of the ions used. The damage will be such as to create point defects (vacancies and interstitials), but not such as to cause amorphisation of the damaged layer. Total doses utilized for carbon, boron and nitrogen are of the order of 10.sup.15 cm.sup.-2 spread over different energies to create a uniformly damaged layer.